High-frequency-oscillation generator or amplifier



April v30, 1946.

- E. U.- CONDON HIGH FREQUENCY OSCILLATION GENERATOR OR AMPLIFIER FiledMarci 14, 1940 WITNESSES:

INVENTOR 'A ORNEY Patented Apr. 30, 1946- rncnrascmsucr-oscmm'rrouassurance on AMPLIFIER Application March 14, 1940, Serial-No. 323,912

10 i'llaims.

My invention relates to electrical oscillators, and has particularrelation to apparatus for generating oscillations having a wave lengthoi the order of decimeters.

It is an object of my invention to provide a decimeter-wave lengthoscillator of simple structure.

Another object of my invention is to provide a decimeter wave lengthoscillator capable of delivering substantial power.

An incidental object of my invention is to promovement is impressed on astream of electrical charges by the electric field of a hollow bodyresonator. As the stream vibrates laterally, it traces a path backwardand forward across a periodicelectromagnetic field, the instantaneousspacial distribution of which is such as to oppose the longitudinalmovement of the charges.

Energy is thus derived from the stream and may be radiated from asuitable antenna.

The novel features that I considericharacteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and.

its method of operation, together with additional objects and advantagesthereof, will best be understood by referringv to the followingdescription taken in connection witlr the accompanying drawing, in whichthe single figure is a diagrammatic viewillustrating a preierredembodiment of my invention.

The apparatus-shown in the drawing comprises a vacuum-tight container inthe form of an elongated ellipsoid of revolution tempered of a metalsuch as copper or stainless steel or an insulator such as glass or aceramic substance. If the container iscomposed of insulating material,-aconducting layer should preferably be deposed on' its inner surface. Thecontainer is in the preferred practice of my invention highly evacuated,although it may contain an inert gas or mercury vapor at a pressure ofseveral microns to several millimeters of mercury.

filament is partially enclosed within a dishshaped metallic shell 5having a small opening? in its base. The shell 5 is preferably groundedand a high negative potential 9 (shown sym bolically as a battery) isimpressed between the filament s and ground. The electrons emitted fromthe filament 3 are accelerated by the potential difierence between theshell 5 and the filament, and concentrated into a narrow beam as theypass through the opening i. To avoid unnecessarily complicating theexplanation, I have shown and described only the filament and theaccelerating shell. In the construction of oscillators in accordancewith my invention, additional electrodes such as are common in thecathode-ray tube art will be found to be desirable. Where suchelectrodes are used in the practice of my invention they are to beregarded as falling within the scope thereof.

The stream of electrons emitted from the open} ing 3 is transmittedthrough an electrical resonator i i which has the form of a hollowdumbbell. The resonator is so disposed that the electron stream passesthrough the center of the constrlcted portion i ii in a directionperpendicular to the longitudinal axis. dumbbell are not of sphericalshape but are preferably ellipsoids of revolution'having a substantialeccentricity with the axes of revolution perpendicular'to thelongitudinal axis of the dumbbell. course take other forms thanellipsoids oi revolution. However, whatever form is selected, it isessential that the major axis of an end should be substantiallydiflerent than the minor axes in the plane perpendicular to thelongitudinal axis 0f the dumbbell. Thus a parallelopiped, the base ofwhich is a rectangle, is one possible form.

Because the ends of the dumbbell lack spherical symmetry. the mode ofelectrical oscillation of the dumbbell in which the electric field isparallel to the direction of the stream is different from its mode ofoscillation in which the electric field is perpendicular to the stream.The

frequency corresponding to the latter mode of oscillation is selectedfor use in the present connection, and the field produced when theresonator is excitedto oscillate in this mode is impressed on thestream. The stream, accordingly, is laterally deflected as indicated bythe diverging arrow lines I! and i9 which-represent" two of itspositions. The deflection is periodic and its frequency is equal to thefrequency corresponding to the selected mode of oscillation of theresonator.

The ends i5 of the The ends of the dumbbell may of To cause theresonator to oscillate in a predetermined manner, the correspondingfrequency must be impressed thereon. Where a system according to myinvention is used for amplifying purposes, a potential corresponding tothe frequency ofthe desired mode of oscillation is impressed from anexternal source. However, in general, my invention is used for theconversion of direct current energy into oscillatory energy. and in sucha case a feed-back coupling from the emitter oi the oscillating energyis provided. For the present, it may be assumed that resonator H isexcited to oscillate at the proper frequency and impresses a periodicdeflection on the electron stream.

After the stream leaves the resonator II, it has a substantial componentof velocity along its original direction in addition to the lateralperiodic component. A second hollow body resonator 2| which ispreferably in the form of a narrow box with the smaller dimension alongthe original direction of motion of the stream is disposed in the pathof the stream and the stream enters the resonator through an elongatedgrid 23 in its incident surface.

The resonator 2|. is so dimensioned that the the upper region theelectric field has one polarity. as indicated by an arrow labeled E andin the lower region, it has the opposite polarity as indicated byanother arrow. The resonators II and -.2l are so spaced and the electricfields at which they are excited to oscillate is so phased that thestream passes through the latter resonator II at any instant at the timewhen the electric field in the region in which it passes is such as tooppose the forward motion of the electrons. The field thus absorbsenergy from the electrons while varying at the frequency correspondingtoits lateral movement.

' The energy derived from the electron stream is to a large extentradiated from an antenna 21 which passes through a hollow tube 23extending from the resonator 2|. In the region in which it is connectedto the resonator 2|, the antenna 21 is provided with a loop 3|, theplane of which is such that the magnetic field corresponding to theelectric field which derives energy from the electrons threads the areabounded by the loop. The loop 3| may be properly oriented in a planeperpendicular to the plane of the arrows 33. a Where the system is to beused for producing oscillations, there is an interchange of energybetween the energy deriving resonator 2| and the deflecting resonator 'iI. The transfer of energy take place through a conductor extending froma loop 31, properly oriented in the deflecting resonator II to a loop 39properly oriented in the deriving resonator 2|. The conductor is ing theresonators. In the deflecting resonator II, the position of the loop 31may be determined by considering the direction of the magnetic fieldcorresponding to the excited mode of oscillation of the resonator. Thedirection of the magnetic field at a series of points is represented bythe curvilinear arrow 43 labeled below the resonator II. The plane ofthe loop 31 should be such that it is threaded by the magnetic fieldrepresented by the ,arrow 43. The loop in the deriving resonator 2|should be oriented to be threaded by the magnetic field represented bythe arrows 33. For the purpose of adjusting the positions of the loops3|, 31 and 39 and timing the resonators H and 2|, magnetically orthermally actuable levers may be provided.

In the direction in which the resonators II and 2| are threaded by thestream of electrons, their dimensions should be so small that the properdeflection of the stream and the efficient derivation of energy is notimpaired by the subiection of the electrons to the held for prolongedtime intervals. These dimensions are determined by taking intoconsideration the selected frequency of oscillation of the resonatorsand the speed of the electrons. The time interval during which anelectron of average velocity i present within the deflecting resonatorII should be so move against the electric field in the region throughwhich they are passing.

After the electrons pass through the absorbing resonator, they aredeflected from a conducting several decimeters may, accordingly, beradiated.

To improve the operation of the resonators, they may be filled with alow loss dielectric material such as rutile.

Although I have shown and described a certain specific embodiment of myinvention, I am fully aware that many modifications thereof arepossible. My invention, therefore, is not to be restricted exceptinsofar as is necessitated by the prior art and by the spirit oi theappended claims.-

I claim as my invention: 1. A hollow body resonator comprising adumbbell shaped bell, the end portions of which have major axes in aplane perpendicular-to the longitudinal axis of the shell, said axesbeing of substantially different length,

2. A generator, detector or amplifier of electrical oscillationscomprising a conducting'shell constituting an electromagnetic resonator,means for projecting a stream of electrical charges through said shell,said shell being so oriented with respect to the line of said chargesthat the electrical field corresponding to one mode of oscillation ofsaid shielded by a conducting tube 4| interconnect. 76 shell imposesonsaid stream a periodic lateral-deflection corresponding to said mode ofoscillation, and another shell, constituting an electromagneticresonator having a mode of oscillation of a frequency substantiallyequal to that of said one mode mounted to receive said charges aftersaid stream has been deflected, said last named shell being so orientedthat the electrical field corresponding to said mode of oscillation ofsaid last named shell is parallel to said stream and is manifested as astanding wave extending between the terminal points between which saidstream oscillates laterally and having a nodal point intermediate ofsaid terminal points, the polarities of the fields at different pointsof said standing wave being such as to oppose the motion of the chargesin said stream.

3. A generator of electrical oscillations comprising a conducting shellconstituting an electromagnetic resonator, means for projecting a streamof electrical charges through said shell, said shell being so orientedwith respect to the line of said charges that the electrical fieldcorresponding to one mode of oscillation of said shell imposes on saidstream a periodic lateral deflection corresponding to said mode ofoscillation, another shell constituting an electromagnetic resonator andhaving a mod of oscillation of a frequency substantially equal to thatof said one mode disposed to receive said charges after said stream hasbeen deflected, said last-named shell being 50 disposed that theelectrical field corresponding to said mode of oscillation of saidlastnamed shell is parallel to said stream and is manifested as astanding wave extending between the terminal points between which saidstream oscillates laterally and having a nodal point intermediate ofsaid terminal points, the polarities of the .fields at different pointsof said standing wave being such as to oppose the motion of the changesin said stream, and means for coupling said shells so that there is aninterchange of energy between them.

4. A generator of electrical oscillations comprising a conducting shellconstituting an electromagnetic resonator, means ior projecting a streamof electrical charges through said shell. said shell being so orientedwith respect to the line of said charges that the electrical fieldcorresponding to one mode of oscillation of said shell imposes on saidstream a periodic lateral deflection corresponding to said mode ofoscillation. and another shell constituting an electromagnetic resonatorand having a mode of oscillation of a frequency substantially equal tothatof said one mode disposed to receive said charges after said streamhas been deflected. said last-named shell being so disposed that theelectrical field corresponding to said mode of oscillation of saidlast-named shell is parallel to said stream and is manifested as astanding wave extending between th terminal points between which saidstream oscillates laterally and having a nodal point in termediate ofsaid terminal points. the polarities of the fields at different pointsof said standing wave being such as to oppose the motion of the chargesin said stream, said shells being so dimensioned in the region in whichthey are penetrated by said stream with reference to the velocity ofsaid stream that the charges of said stream reacts with an electricalfield which is substantially constant for all practical purposes duringthe time that said charges are subjected to said field.

5. Apparatus for generating electrical oscillations comprising means forprojecting a stream of electrical charges, means for swinging saidstream laterally at the periodicity of said oscillations, and means forproducing a periodic electromagnetic field having the periodicity ofsaid oscillations in the path of said stream, the electric vector ofsaid field being substantially along the line of said stream and havinga polarity opposite to that of said stream in the region .in which saidstream impinges on said field at any instant and having the oppositepolarity at the same instant in a contiguous region.

6. In combination, a conducting shell constitutin an electromagneticresonator and having two end portions and a constricted portion join-aing said two end portions, mean for passing a stream of electronsthrough said constricted portion of said shell only, said shell being soshaped that the electric field corresponding to one mode of oscillationof the shell is at substantially right angles to said stream, and meansfor producing oscillations in said shell in said'one mode whereby aperiodic lateral deflection of said stream is effected.

'7. In combination, a conducting shell constituting an electromagneticresonator and having a constricted portion. means for passing a streamof electrons through said constricted portion of said shell only, saidshell being so shaped that the electric field corresponding to one modeof oscillation of the shell is at substantially right angles to saidstream, means for producing oscillations in said shell in said one modewhereby a periodic lateral deflection of said stream is effected, andmeans for producing a periodic electromagnetic field having theperiodicity of said oscillations in the path of said stream after it haspassed through said shell, the electricvector of said field beingsubstantially along the line of said stream and having a polarityopposite to that of said stream in the region in. which said streamimpinges on said field at any instant and having the opposite polarityat the same instant in a contiguous region.

8. In combination, aconducting shell constituting an electromagneticresonator and having a constricted portion, means for passing a streamof electrons through said constricted portion of said hell only, saidshell being so shaped that the electric field'correspondlng to one modeof oscillation of the shell is at substantially right angles to saidstream, means for producing oscillations in said shell in said one modewhereby a periodic lateral deflection of said stream is effected, andanother shell constituting an electromagnetic resonator having acorresponding mode of oscillation of a frequency substantially equal tothat of said one mode mounted to receive said stream of electrons afterdeflection thereof, said last named shell'being so oriented that theelectrical field of said corresponding mode of oscillation is parallelto said stream and is manifested as a standing wave extending betweenthe terminal points between which said stream oscillates laterally andhaving a nodal point intermediat of said terminal points, the polaritiesof the fields at different points of said standing wave' being such as toppose the motion of the electrons in said stream.

9. The combination of a hollow body resonator comprising a dumb-bellshaped shell having a constricted center portion and a pair of endportions, the end portions having major axes in a plane perpendicular tothe longitudinal axis of the shell. said axes being of substantiallydifferent length, means for projecting a stream of electrical chargesthrough said constricted center portion in a direction perpendicular tothe electric field corresponding to one of the modes of oscillation ofsaid shell, and means for producing oscillations in said shell in saidone mode whereby a periodic lateral deflection of said stream isefiected.

10. The combination 0! a hollow body resonator.

comprising a dumb-bell shaped shell having a constricted center portionand a pair or end portions, the end portions having major axes in aplane perpendicular to the longitudinal axis or the shell, said axesbeing or substantially different length, means for projecting a streamof electrical charges through said constricted center portion in a.direction perpendicular to the electrio field corresponding to one ofthe modes of oscillation of said shell, means for producingoscillationsin said shell in aid one mode whereby a periodic lateral deflection ofsaid stream is tiguous region.

EDWARD U. CONDON.

